<html>
<head>
<script type="text/javascript">
function getCookie(c_name) {
	if(document.cookie.length > 0) {
		c_start = document.cookie.indexOf(c_name + "=")
		if(c_start != -1) {
			c_start = c_start + c_name.length + 1
			c_end = document.cookie.indexOf(";", c_start)
			if(c_end == -1) c_end = document.cookie.length
			return unescape(document.cookie.substring(c_start, c_end))
		}
	}
	return "";
}

function setCookie(c_name, value, expiredays) {
	var exdate = new Date()
	exdate.setDate(exdate.getDate() + expiredays)
	document.cookie = c_name + "=" + escape(value) +
		((expiredays == null) ? "" : "; expires=" + exdate.toGMTString())
		
	//username=test; expires=失效日期的时间
}

function checkCookie() {
	username = getCookie('username')
	if(username != null && username != "") {
		alert('Welcome again ' + username + '!')
	} else {
		username = prompt('Please enter your name:', "")
		if(username != null && username != "") {
			setCookie('username', username, 365)
		}
	}
}</script>
</head>
<body onLoad="checkCookie()">
</body>
</html>
